STUDY ON PHENOLOGY HEAT-USE EFFICIENCY AND YIELD PERFORMANCE OF WHEAT UNDER HIGH TEMPERATURE STRESS CONDITION

Abstract

The study was undertaken at the research farm and laboratory of Crop Physiology and Ecology Department, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during November 2015 to April 2016 to study on phenology, heat-use efficiency and yield performance of four wheat genotypes under normal and late growing heat stress conditions. The experimental treatments included sowing conditions- normal sowing condition (sowing at November 30), late sowing condition (sowing at December 30) and four wheat varieties such as BAW-1170, BARI Gom 25, BARI Gom 26 and E 22. The experiment was laid out in split plot design with three replications. Results revealed the number of days for attaining different phenological stages, the requirement of heat unit (GDD) and heat-use efficiency (HUE) were higher for normal growing condition compared to late growing condition. Wheat genotypes BAW-1170, BARI Gom 25, BARI Gom 26 needed higher number of days, GDD and HUE for different phenological stages compared to E 22 in both the sowings conditions. All the genotypes showed a common tendency of higher PSR mobilization to grain under late growing high temperature stress condition. Irrespective of growing conditions genotype E 22 showed higher pre-anthesis stem reserves (PSR) mobilization to the final grain weight compared to BAW-1170, BARI Gom 25, and BARI Gom 26. Genotypes BAW-1170, BARI Gom 25, BARI Gom 26 showed higher canopy temperature depression (CTD) in both the growing conditions than the E 22. The late sowing high temperature stress condition significantly reduced the flag leaf area, chlorophyll and sugar content, plant height, spike length, number of spike per plant, number of kernel per spike, grain weight per spike and 1000 grain weight, flag leaf proline. Genotype BAW-1170 attained the highest flag leaf area, chlorophyll of flag leaf at 8 days after anthesis, flag leaf sugar at 16 days after anthesis, plant height, spike length, number of spike per plant, number of kernel per spike, grain weight per spike, 1000 grain weight and flag leaf proline, whereas genotype E 22 showed the lowest value of those parameter at both the sowing conditions. In these characters the relative performance was highest in BAW1170 and the lowest in E 22, whereas BARI Gom 25 and BARI Gom 26 showed intermediate relative performance. Finally, in yield parameter, genotype E 22 showed lower performances in both the growing conditions compared to other genotypes. At late growing condition, the grain yield and biological yield of all genotypes were significantly reduced at different magnitude compared to normal growing condition. Genotypes BAW-1170, BARI Gom 25, BARI Gom 26 attained higher relative yield compared to E 22. From heat susceptibility index it was observed that BAW-1170 and BARI Gom 26 were clearly lower heat susceptible (S<1.0) in grain yield compared to other genotypes. The results of present study suggested that greater growth duration minimize the changes in flag leaf chlorophyll, proline content in flag leaf, less dependence on stem reserves mobilization, ability to maintain a cooler canopy environment reflected on yield and important yield determinants and those can be considered as selective criteria of heat tolerance in wheat.